doc: Add link to login event trigger example

The login event trigger is not listed on the trigger firing matrix
since it's not fired by a command.  Add a link to the example code
page similar to how the other event triggers link to the matrix.

Reported-by: Marcos Pegoraro 
Discussion: https://postgr.es/m/CAB-JLwYS+78rX02BZ3wJ9ykVrd2i3O1K+7jzvZKQ0evquyQiLQ@mail.gmail.com

diff --git a/doc/src/sgml/event-trigger.sgml b/doc/src/sgml/event-trigger.sgml
index 8e009cca050f2def75f384f0bbfc3deb2e20c151..d03063903465748bf12db36c9f8c7b38b5de58df 100644 (file)
--- a/doc/src/sgml/event-trigger.sgml
+++ b/doc/src/sgml/event-trigger.sgml
@@ -54,6 +54,11 @@
      the in-progress login trigger.
    
 
+   
+     For an example on how to use the login event trigger,
+     see .
+   
+
    
      The ddl_command_start event occurs just before the
      execution of a CREATE, ALTER, DROP,